Reciprocal dual circuit breaker double interlock mechanism



IIII A U l I V Nov. 21, 1950 E. A. PIFKE RECIPROCAL DUAL CIRCUIT BREAKER DOUBLE INTERLOCK MECHANISM 2 Sheets-Sheet 1 Filed Aug. 18, 1949 Ifive'ntor: Ecjgar A. PifKe His Attorney.

Nov. 21 1950 E. A. PIFKE ascxraocm. nun. cmcurr BREAIER DOUBLE m'rsmocx umcnmxsu 2 Sheets-Sheet? Filed Aug. 18, 1949 44 4 I Inventor Edgar A.PifKe,

His Attorney.

Patented Nov. 21, 1950 UNITED STATES PATENT OFFICE BECIPROCAL DUAL CIRCUIT BREAKER DOUBLE INTERLOCK MECHANISM Edgar A. lii'ke, Philadelphia, Pa., assignor to General Electric Company, a corporation of New York 8 Claims.

The invention relates to circuit breaker interlock mechanism and the principal object is to provide an improved reciprocal double interlock mechanism for more effectively insu in against the simultaneous closure of two separately operable interconnected circuit breakers particularly of the trip-free latch type.

When two breakers are interconnected in various systems the simultaneous closure thereof may be dangerous, or even disastrous. Thus, in a multiphase alternating current motor reversing systern where one breaker produces forward operation and the other breaker produces reverse operation by reversal of the phases, the simultaneous closure of the two breakers may produce a dead short on the power lines. Likewise, where one breaker energizes alternating current power lines from one source and the other breaker energizes the po er lines from another source, a dangerous condition may result in case of simultaneous closure of the breakers in the absence of synchronization. In many other systems the simultaneous closure of the two latch-type breakers intentionally or even accidentall by shocks or jars may produce unsafe conditions. Thus another object is to interlock two tripfree latch-type circuit breakers so that the closure of either breaker will not only actuate the latch trip element of the other, but also mechanically lock a. closing member of the other breaker in the open position thus doubly insuring against the simultaneous closure of the two breakers.

Another object is to obtain reciprocal double interlocking by means of simplified connections having a pair of juxtaposed reciprocating links extending between the breakers and each mechanically connected with a corresponding breaker closing member for movement in a direction opposite to the other upon closure of the corresponding breaker and each provided with a cam mechanism for actuating the trip element of the other breaker during the initial movement of the interconnected link in the breaker closing direction and also with a lost-motion interlock element for engaging with an opposite interlock element of the other link upon completion of the closing movement for blocking the opposite movement of the other link and thereby preventing closure of the breaker connected with the other link.

Other objects and advantages of the invention will appear in the following description of the accompanying drawing in which Fig. l is a side view of two superimposed typical circuit breakers or the manually closed trip-free latch-type pro- 2 vided with the improved double interlock mechanism of the present invention; Fig. 2 is a perspective view showing more clearl the simplified interlocking connections between the two separate circuit breaker operating members and the two respectively corresponding circuit breaker trip elements that provide reciprocal double interlocking therebetween; Fig. 3 is a partial view showing the relative positions of the interlocking parts when the lower one of the two breakers is closed; and Fig. 4 is a similar partial view showing the relative positions of the interlocking parts when the upper one of the two breakers is closed.

As shown in Fig. 1, two typical breakers indicated generally by the reference character 10 and H are mounted one above the other on a base panel l2. The two circuit breakers ma be of any well-known trip-free latch type having suitable means such as, for example, the rotatable manual operating handles l4 and I5 for separately closing the respective breaker. Hence the various structural details of the breaker closing and latching mechanisms are not shown in order to avoid unnecessary complications, although each as outlined in the drawing is of the improved type more fully described and claimed in the Favre application S. N. 775,573, filed May 15, 1946, which is assigned to the present assignee.

It will be understood that the handle i4 operates suitable mechanism (not shown) that effects movement of the circuit breaker operating bar or closing member [8 to the right so as to move one or more contacts I8 into engagement with corresponding stationary contacts 20 through the agency of the interconnecting link 22. In a similar way, the circuit breaker operating bar or closing member ll of the lower circuit breaker H effects the engagement of one or more movable contacts l9 with corresponding stationary contacts 2| by means of the interconnecting link 23 when the operating handle I5 is rotated. However. if desired, operation of the circuit breaker closing members 16 and I! may also be effected by suitable closing solenoids, not shown. It will be further understood that in each case the closing member It or I! is latched in its closing position by suitable trip-free latching mechanism, not shown, which is arranged to be tripped upon counterclockwise rotation of the trip shafts 2B and 21 respectively. As indicated these trip shafts having trip arms 20 and 29 carried thereby for operation by suitable overload responsive automatic tripping mechanism 30 and 3| and also are provided. with the auxiliary trip arms 32 and 33 for interlocking purposes in accordance with the present invention.

In further accordance with the present invention, separate interlocking connections between the closing member of each breaker and the tripping element of the other breaker for moving the element to its tripping position upon movement of the member towards its closing position are provided. Thus as shown in Figs. 1 and 2, the closing member I6 of the upper breaker I0, is connected to a bell crank 36 having a fixed pivot axis 31 carried by the supporting arm 38 extending from the mounting base I2 and provided with an elongated slot 39 for receiving the closing member I6 therein and the bell crank 36 is connected to a link 40 by means of the pivot pin 4|. The link 40 i overlapped by the juxtaposed link 42 and carries the two guide pins 43 sliding in slots 34 formed in link 42 to permit relative reciprocating movement of the two links in opposite directions. The lower end of link 40 carries an operating pin 44 slidable in a substantially J-shaped cam slot 45 formed in the cam member 46 that is pivotally mounted on the axis pin 41 carried by the bracket 48. Thus, when the closing member I6 of the upper circuit breaker I6 is initially moved towards its closing position, bell crank 36 is rotated counterclockwise to raise the link 40 and thereby move pin 44 in the lower curved portion of the J-slot 45 so as to eifect rotation of the cam member 46 in the clockwise direction to lift the trip arm 33 by means of the adjustable finger 35 and thus rotate the trip shaft 21 to its tripping position. The straight part of the J-shaped cam slot 45 serves to maintain the shaft 21 in its tripping position during the completion of the movement of the circuit breaker closing member I'6 to its closing position as indicated in Fig. 4. v

The closing member I I of the circuit breaker I I is connected to the bell crank 49 having its fixed pivot pin 50 carried by the supporting element 5| and provided with an elongated slot 52 for receiving the closing member l1 therein. One end of the bell crank 49 is pivotally interconnected with the lower end of the juxtaposed link 42 by the pivot pin 53 and the upper end of link 42 carries a cam operating pin 54 in sliding engagement with the cam 55 that is pivotally mounted on the pin 56 carried by the supporting arm 51 so as to engage the adjustable operating finger 58 with the actuating arm 32 of the trip shaft 26 and thereby move the trip shaft to its tripping position during the initial movement of the circuit breaker closing member I1 towards its closing position. The pin 54 cooperates with the cam 55 to maintain the trip shaft 26 in its tripping position during the completion of the closing movement of the closin! member IT as indicated in Fig. 3.

In further accordance with the present invention, a lost-motion mechanism is provided for interlocking the juxtaposed oppositely movable links 46 and 42 so as to prevent movement of the other circuit breaker closing member to its closing position when either circuit breaker circuit closing member is in its closing position, thereby providing the improved double interlocking feature. This is accomplished bv simpl nrovid nrr the link 42 with a supporting bracket 66 carrying the adjustable stop 6I opposite the end of the guide pin 43 that is carried by the juxtano ed link 46. Thus, when link 40 is raised upon closure of the circuit breaker III to operate the trip element 21 of circuit breaker I I to its tripping position and maintain the element therein as in- (ill dicated in Fig. 4, the end of the guide member 43 is brought into engagement with the adjustable stop 6I upon the completion of the closing movement of the closing member I6. S uch engagement of the opposite stop members 6I and 43 effectively blocks the link 42 against downward movement and thereby holds the bell crank 46 in the position in which it is shown in Fig. 4 so as to prevent any substantial movement of the closing member I! of the circuit breaker II towards its closing position. Such double interlocking effectively insures against any accidental closure of the circuit breaker II while the circuit breaker I0 is in its closed position. Thus, with trip shaft 21 in its tripping position and closing member I1 mechanically blocked against movement towards its closing position, rotation of the operating handle I 5 or operation of a closing solenoid or shocks or vibrations are unable to effect closure of the circuit breaker II while circuit breaker I6 is closed.

Conversely, when circuit breaker II is closed as indicated in Fig. 3, the resulting engagement of the adjustable stop 6| carried by the link 42 with the cooperating stop 43 carried by the juxtaposed link 40 eilectively blocks upward movement of the link 40 thereby holding the bell crank36 in its position in which it is shown in Fig. 3 so as to mechanically lock the closing member I6 of the circuit breaker I6 against movement towards its closing position. Thus, due to the double interlocking provided by the mechanical locking of closing member I 6 against movement in the closing direction and the maintenance of tripping member 26 in it tripping position. rotation of the handle I4, operation of the closing solenoid or jars or vibrations are ineffective to close the circuit breaker I 0 while the circuit breaker II is closed. Furthermore, the improved double interlocking of the present invention insures that in the event of failure to mechanically block each circuit breaker in the open position when the other circuit breaker is closed due to failure of the bracket 60 or the adjustable stop 6I, still simultaneous closure of the two breakers may be effectively prevented since the initial closing movement of each breaker will always trip the latch of the other breaker to effect the opening thereof if the other breaker is closed or prevent the closing thereof it the other breaker is open.

What I claim as new and desire to secure by Letters Patent 01' the United States is:

1. In combination, two circuit breakers, each having closing means including a movable c osing member and tripping means including a movable tripping element, separate interlocking connections between the closing member of each breaker and the trippin element of the other breaker for moving the element to its tripping position upon movement of the member towards its closing position, and lost-motion mechanism for interlocking said connections to prevent movement of the other closing member towards its closing position when either member is in its closing position.

element in its tripping position during the compietion of said movement, and means including lost motion engageable elements for interlocking said connections to prevent substantial movement of the other member towards its closing position when either member is substantially in its closing position.

3. A reciprocal double interlock for two sepa-- rate circuit breaker closing members and two respectively corresponding circuit breaker tripelements comprising a separate interlocking connection between each closing member and the non-corresponding trip element for moving the trip element to its trip position when the interconnected closing member is moved towards its closing position. and lost-motion mechanism for ment of the other member and thereby doubly.

preventing simultaneousclosure o! the breakers. 5. A reciprocal dual. circuit breaker double interlock mechanism having, in combination, two

juxtaposed separately movable. members, each having with a corresponding one 01' the circuit breakers for movement in a direction to the other member during closure or the corresponding breaker and each provided prising a juxtaposed pair or oppositely movable 7. A reciprocal dual circuit breaker double 'interlock mechanism having, in combination, two

separate circuit breaker operating members selectively movable in the same direction from one pmition'to another to close the corresponding breaker, two separate corresponding circuit breaker trip members, each independently movab e in the same direction from an inactive position to the circuit breaker trip position, separate connections between each operating member and the non-corresponding trip member for moving the connected trip member to the trip position when a selected operating member is inithlly moved away from the one position towards the other position, and said connections having adjacent members movable in opposite directions to eflect movement of the non-corresponding trip member in the same direction. and each of said adjacent oppositely movable members having an interlock with the other mernber ior locking the non-selected operating member in the one position while the selected operating member is in its other position.

8. A reciprocal dual circuit breaker double interlock mechanism having in combination, two separate circuit breaker operating members mounted ior reciprocating movement in parallel paths and selectively movable in the same direction to close the corresponding breaker, two separate corresponding circuit breaker trip membiss mounted ior rotation about parallel axes in the same direction to trip the corresponding breaker, separate interlock connections between each operating member and the non-corresponding 'trip member, each connection including a reciprocating link and a cooperating cam mechanism for moving the connected trip member to the trip position when a selected operating membe is initially moved in the direction to close the corresponding breaker and said reciprocating members and cooperating cam mechanism proriding for movement of the reciprocating links in opposite directions upon movement 0! the connected trip member in the circuit breaker tripping direction. and each of said opposite reciprocating links having an interlock element unusable with the interlock element of the other for locking the non-selected operating mmbaagainst movement in the circuit breaker closing direction upon completion 0! the movementorthecorresponding circuitbreaker trip member in the circuit breaker tripping direction.

IDGARAPII'KE.

REFERENCES CITED 'lheioilowingreferencesareoirecordinthe medthispatent:

UNITED STATES PATENTS Name Date Scott Dec. i8, 191'! Number 

